Refractory brick for use in suspended roofs



March 26, 1968 c. A. TATE 3,374,594

REFRACTORY BRICK FOR USE IN SUSPENDED ROOFS Filed Jan. 30, 1964 I /2 Ill //v VEA/ 70 Hg. 5 CARL A. 7:475

United States Patent 3,374,594 REFRACTORY BRICK FOR USE IN SUSPENDEDROOFS Carl A. Tate, Pittsburgh, Pa., assignor to Harbison-WalkerRefractories Company, Pittsburgh, Pa., a corporation of PennsylvaniaFiled Jan. 30, 1964, Ser. No. 341,450 2 Claims. (Cl. 52-598) Thisinvention relates to blocks or brick from which suspended refractoryroofs for furnaces and the like are formed, and more particularly tocomposite blocks formed from basic refractory shapes and sheet metal.

Suspended refractory roofs, for example the open hearth roof, frequentlyare formed from basic brick which are individually supported from theirupper ends by metal hangers. Between the individual brick are plates ofmetal, usually mounted on the brick themselves. When the furnace isheated, the metal plates increase in thickness to tighten the roof andform a monolith-like structure. The advantages of such a constructionare well known and are disclosed in several patents. See, for example,the US. patent to Rochow, No. 2,465,170, entitled, Metalcased CompositeSuspended Roof Unit; Mason et al., US. Patent No. 2,846,963, entitled,Reinforcing Insert for Furnace Block; Myers et al., US. Patent No.2,961,805, entilted, Encased Refractory Brick; and Heuer, US. Patent No.2,652,793, entitled, Refractory Furnace Roof Brick Resistant toSpelling.

A common form of hanger device for suspending these metal encased basicrefractory blocks or brick is comparable in design to an inverted T.With this invented T hanger device, a block is suspended from each sideof the crossbar. Opposed adjacent faces of such a pair of blocks arephysically in face-to-face contact.

Particularly with the newer developments in open hearth roofconstruction, in which the entire roof is mounted in rigid assembly,with almost no allowance for expansion and contraction, it has becomeevident to me that the abutting faces of a given pair of blocks or bricksuspended from one of the inverted T-shaped hangers should preciselymatch. There should be substantially no overhang evident when a givenpair of brick are mounted.

Many forms of refractory brick construction have been suggested toaccommodate the T-shaped or like hanger. A few are noted above. Anotherone is disclosed in US. Patent No. 2,517,876, to Heuer entitledRefractory Brick for Use in Suspended Furnace Roofs. This Heuer patentdiscloses use of an inverted U-shaped device arranged to be comoldedwith a brick.

As those skilled in the art of refractory brick manufacture realize,uniformity of brick dimension must be carefully controlled. Such controlis not particularly easy. Substantially equal weight quantities ofbrickmaking material must be fed to the press if one wishes to obtain agroup of brick of uniform dimensions and physical properties. Also,there must be substantially uniform forming pressure exerted to makeeach brick. Of course, when I refer to physical properties herein, Imean to include such things as density, porosity, thermal conductivity,modulus of rupture and so forth.

It is my opinion that prior practices of providing means in a refractorybrick or block by which the brick or block is to be suspended, havetended to be at cross purposes to the desired substantial uniformity ofbrick dimension and physical properties. Most of the prior methods havecalled for comolding of a shape and some manner of metal hanger elementto form a composite structure. Such comolding procedures, my opinion,tend to cause nonuniform densification of a brick adjacent the coldface. Very often the metal insert is deformed to such an extent thebrick cannot be used. Further, with minor variation in 3,374,594Patented Mar. 26, 1968 pressing pressure and in quantity of charge tothe press, the relative positioning of these metal devices from brick tobrick is almost an uncontrollable factor. I realize means could bedevised to assure substantially uniform positioning of these metaldevices from brick to brick even though they are comolded. However, sucharrangements would undesirably increase the cost of manufacture.According to this invention, I provide a novel method of fabricating acomposite refractory brick for use in suspended roofs which is veryeasily practiced, requires no expensive tools or press modifications,and reduces the overall raw materials cost as compared to prior methods.

It is another object of this invention to provide a novel compositerefractory shape suitable for use in fabricating suspended furnaceroofs.

Briefly, according to one embodiment of this invention a compositerefractory shape is provided which consists of a generally rectangular,chemically bonded, basic refractory brick that is metal encased andpreferably'has internal reinforcing plates. This much is common to theart as shown, for example, in many of the patents above identified.Adjacent the end of the brick which is to serve as the cold end (ie. theend of the brick farthest removed from the metallurgical process hightemperatures) a polarized notch or cut-out is formed. This notch isformed during the pressing of the brick. It is made, for example, by aprotuberance on the top pressure plate of a brick press so the polarizednotch is formed during pressing of the shape. A tubular metal device ofcomplementary polarization is cemented in the notch. Of course, theinsert can be friction fitted if desired. Since the same upper plate isused to fabricate each brick, each brick has its suspending structure inprecisely the same position. Further, because the pressure plate ismachined from quality steal, it is possible to accurately duplicate aseries of top pressure plates and notch forming protuberances.

, A better understanding and other objects and advantages of this brickconstruction will become readily apparent to those skilled in the artfrom a study of the following detailed description together with thereferenced drawings.

In the drawings:

FIG. 1 is a schematic view with some parts broken away to better showthe internal arrangement of parts of brick construction according tothis invention;

FIG. 2 is an enlarged fragmentary schematic view of the upper end of thebrick of FIG. 1 and the tubular insert immediately prior to assembly;

FIGS. 3 and 4 are alternative insert constructions; and

FIG. 5 is a schematic view of a top pressure plate which can be used tomake the bricks of FIGS. 1 and 2.

Before describing the drawings in detail, it should be understood theyare but exemplary of the best modes now known to me for the practice ofmy invention and should not be considered limiting. Rather, the spiritand scope of this invention is as defined in the hereafter appendedclaims.

Most basic open hearth roof brick are basic in character. That is, theyare fabricated of materials, for example, selected from the group deadburned magnesia, chrome ore, dead burned dolomite, and so forth.Commerically available ones which are often used are brick made entirelyof chrome ore, ones made entirely of magnesia, ones made of a mixture ofchrome ore and magnesia in which the chrome ore constitutes from 50 toby weight, of the total brick, which brick are termed chromeore-magnesia brick, and brick made from a mixture of magnesia and chromeore in which the magnesia predominates and constitutes on the order of50, and more usually 60 to 80%, of the total brick. These later brickare termed magnesia-chrome ore" brick.

As is understood by refractory technologists, brick made on a brickpress are formed from a semi-dry, size graded, granular material. Thegranular material is so size graded as to provide good packing whensubjected to the action of the brick press to thereby obtainselfsustaining, handleable shapes. Size grading may be, for example,about 30%, by weight, 3+10 mesh, about 20% 10+65, the rest passing a 65mesh screen. This latter 65 mesh batch component is sometimes referredto as ball mill fines in the refractory brickmaking aft. Ball mill finesusually have from 40 to 60% held on a 325 mesh screen. 'I hese sizingsare all Tyler series. This size graded granular brickmaking material isusually tempered with a minor amount of a fluid, for example, 4 or 5% ofwater, a water-lignin liquor mixture, water and dextrine, cornstarch,etc. Thus, fabrication of refractory brick on a brick press is quite adifferent art from treatment of very fine powders such 'as are used forthe production of electrical porcelains, cutting tools and the like; andwhile related, is, of course, quite distinct from the art of makingshapes from wet or plastic mixtures such as 'are used to make ordinaryred clay building brick, concrete blocks, etc.

A composite unit of this invention is comprised of an unburned orchemically bonded basic refractory block -11 having a polarized notch 12formed in an upper edge thereof, which edge is formed by theintersection of the upper or intended cold end of the brick and one ofthe larger side faces. A two-piece overlapping metalcase construction iscarried on the block or brick 11. I prefer that this case be installedaccording to the teachings of the US. patent to Cotfman et al., No.2,736,187 entitled, Composite Furnace Block. Of course, otherarrangements can be used such as, for example, gluing the case to thebrick, by punching ears through the case and into the brick body, etc.Further, while I prefer a metal sheath about the four long sides of therefractory shape, a single U-shaped metalcase is satisfactory for someuses. Alternatively, one U-shaped case can be used for three sides and aseparate, flat plate can be applied to the fourth side.

The brick 11 can include a pair of internal metal reinforcing plates 13installed, for example, in the manner taught in US. Patent No.3,082,503, of Myers et al., entitled, Method of Comolding a Metal Insertin a Brick. It should be understood such plates are not necessary. Infact, I believe, in some instances, it is desirable to omit them inorder to obtain still better dimensional accuracy and uniformity ofdensification in the brick.

The notch 12, which is formed in the upper edge of the brick 11,generally can be characterized as having a truncated triangular crosssection. Adhesively mounted by cement 14a in that notch is a tubularinsert 14 of complementary shape.

A particularly desirable aspect of tubular inserts, such as, the insert14, is that they may be made by cutting lengths from an extruded tubehaving substantially uniform cross sectional dimensions from one end tothe other. They may be drawn from roundtubing. The inserts 14 are easilyinserted in the preformed notch 12. Since the notch 12 and the insert 14are of very precise dimensions, the resulting composite shape issubstantially identical to other shapes made of inserts cut from thesame tube and made on the same press (or other presses having anidentical protuberance formed on one of the pressure plates).

FIG. 5 shows a pressure plate with the protuberance 21 as an integralpart thereof. If desired, the plate and protuberance combination can becast and then machined to dimension or the protuberance 21 can be formedfrom a separate piece of stock which is subsequently welded to the plate21. Of course, the resultmg welded combination would be mac ined tassure dimensional accuracy.

While I prefer the truncated triangular configuration as shown in FIGS.1 and 2, other polarized shapes may be used. For example, shapes 30 and31 shown in FIGS. 3 and 4.

I prefer that the notch 12 be formed through an edge. It is easier tomaintain dimensional accuracy. However, the polarized notch can beformed through a side surface of the brick a short distance below theintended cold face of the brick. However, I do not suggest this as themost satisfactory manner of accomplishing a composite brick constructionaccording to this invention. One reason is because the resulting wall orthicknes of brick between the cold end and the notch is susceptible tobreakage and cracking.

I prefer that the portion of the outer metal casin which covers the sideface through which the polarized notch is formed, be itself notched orcut as, for example, thenotch 22 on the case 23 in FIG. 1. Such anarrangement assures maximum coverage of the face of the brick throughwhich the notch is formed. Of course, if one desires, a short plate canbe used which terminates just below the notch 12.

The preferred embodiment of this invention is the arrangement shown inFIG. 1, and the brick is of the magnesia-chrome ore type. Preferably thebrick contains between 60 and dead burned magnesite of the typedisclosed and claimed in US. Patent 3,060,000, of Snyder et al.,entitled, Production of Dead Burned Magnesia. The remainder of the brickis refractory grade chrome ore; I prefer Philippine chrome ore. Thesizing of the ingredients is substantially, as set forth above,referring to typical size grading for this type of brick. In a 9 by 4%by 3 inch brick, the notch and the complementary insert can be about 2inches in height, about 3 inches in width at the widest point and about2 inches in depth.

Having thus described the invention in detail and with sufficientparticularity as to enable those skilled in the art to practice it, whatis desired to have protected by letters patent is set forth in thefollowing claims.

I claim:

1. A composite refractory shape comprised of a refractory body havingopposed ends and sides extending between the ends, an aperture formedthrough an intersecting side and end said aperture having a base andsidewalls which converge to form a narrow aperture at one of the ends ofsaid body, a tubular oxidizable metal insert of cross-sectionalconfiguration mating the crosssection of said aperture, said insertfixed in said aperture and filling the cross-section thereof, saidinsert being fixed against upward and downward movement perpendicular tothe ends of said body, the said metal insert having at least one planarouter face which is substantially coplanar with the remainder of the endof the shape through which the aperture is formed.

2. The shape of claim 1 in which said insert is adhesively mounted inthe aperture.

References Cited UNITED STATES PATENTS 2,930,601 3/1960 Hever llO993,204,586 9/1965 Marsh -99 3,086,327 4/ 1963 Samuel et a1. 522703,234,703 2/1966 Sullivan 52596 3,292,333 12/ 1966 Sandmeyer et a1.52--509 FOREIGN PATENTS 927,632 5/1963 Great Britain. 865,537 3/1941France. 1,278,173 10/ 1961 France.

FRANK L. ABBOTT, Primary Examiner.

JAMES L. RIDGILL, JR., Examiner.

1. A COMPOSITE REFRACTORY SHAPE COMPRISED OF A REFRACTORY BODY HAVINGOPPOSED ENDS AND SIDES EXTENDING BETWEEN THE ENDS, AN APERTURE FORMEDTHROUGH AN INTERSECTING SIDE AN END SAID APERTURE HAVING A BASE ANDSIDEWALLS WHICH CONVERGE TO FORM A NARROW APERTURE AT ONE OF THE ENDS OFSAID BODY, A TUBULAR OXIDIZABLE METAL INSERT OF CROSS-SECTIONALCONFIGURATION MATING THE CROSSSECTION OF SAID APERTURE, SAID INSERTFIXED IN SAID APERTURE AND FILLING THE CROSS-SECTION THEREOF, SAIDINSERT BEING FIXED AGAINST UPWARD AND DOWNWARD MOVEMENT PERPENDICULAR TOTHE ENDS OF SAID BODY, THE SAID METAL INSERT HAVING AT LEAST ONE PLANAROUTER FACE WHICH IS SUBSTANTIALLY COPLANAR WITH THE REMAINDER OF THE ENDOF THE SHAPE THROUGH WHICH THE APERTURE IS FORMED.